Low insertion force card edge connectors are known wherein a circuit card which is inserted into the connector with a straight line motion at a first angular orientation experiences minimal insertion resistance. The card is then pivotable to a second angular orientation wherein contact pads on the circuit card engage contacts in the connector and deflect the contacts so as to create a normal force between each contact and its associated contact pad. The card is secured in the second orientation by latch members.
U.S. Pat. No. 4,737,120 discloses a low insertion force card edge connector having contacts with first and second contact portions extending from a base. The first and second contact portions are independently pivotable about their junctions with the base, and each of the contact portions has a projection which engages a respective contact pad on the circuit card. A problem with these contacts arises when the circuit card is bent or warped out of its plane. In that case one or more of the contact portions may not be deflected enough to create a normal force sufficient to ensure a good electrical connection with its associated contact pad.
In order to provide a greater tolerance for circuit cards of different thickness and for cards that are bent or warped out of their plane, contacts have been configured with opposed contact projections disposed on a continuous member which is pivotably connected to the base at a single pivot point. U.S. Pat. No. 4,984,996 discloses such a contact having an upstanding spring arm (25) extending from a base (24) upwardly to a connection beam and extending through a reverse loop to a C-shaped section (26). First and second contact points (25a, 26a) are defined at opposite ends of the C-shaped section. This contact is forgiving of circuit card dimensional variations because both of the first and second contact points (25a, 26a) can pivot with the C-shaped section (26) as an integral unit about the pivotal connection of the spring arm (25) with the base. Accordingly, the spring arm (25) must have a clearance on either side to permit pivoting, and this clearance adds to the overall dimensions of the connector. It should be noted that during insertion of the circuit card in this connector, the circuit card is pivoted toward the attached end of the C-shaped section, i.e., toward the reverse loop and toward the spring arm. Pivoting the card in this direction causes the reverse loop to be put in tension as the card acts on the contact point (26a), and the connection beam between the reverse loop and the spring arm (25) to be put in compression.
A similar contact is disclosed in U.S. Pat. No. 5,080,602. Here, the contact includes a spring arm (24) extending upwardly from a pivot portion (23) to a connection beam and extending through a reverse loop downwardly to a C-shaped section which has contact points (25, 27) at opposite ends. Again, the card is pivoted toward the reverse loop and the spring arm, thereby tensioning the reverse loop and compressing the connection beam, and clearance must be provided for the spring arm (24) to flex about the pivot portion (23).
The present invention provides a low insertion force connector having contacts which do not rely on a spring arm to supply normal force to the circuit card. Instead, the card is pivoted in a direction away from the stress loop, and a reaction force of the contact loop puts the reverse loop in compression, thereby generating a normal force on the card.